Summary

Fixes the regression on ember-lts-4.12 introduced by #323:

Uncaught ReferenceError: Cannot access 'getOwner' before initialization
at http://localhost:.../assets/app-*.js, line N

Root cause

ember-source >= 4.12's @ember/application/index.js re-exports getOwner/setOwner from @ember/owner under aliases, then reassigns them as consts:

import {
  getOwner as actualGetOwner,
  setOwner as actualSetOwner,
} from '@ember/owner';

export const getOwner = actualGetOwner;
export const setOwner = actualSetOwner;

babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner (added in #323) rewrote the from '@ember/owner' at the top of that file to from '@ember/application' — the module's own specifier — so rollup bundled it as a self-import. The const getOwner = actualGetOwner line then becomes (effectively) const getOwner = getOwner, which trips TDZ at load time.

The plugin already tries to skip ember-source files with this guard:

if (state.filename?.includes('/ember-source/')) {
  if (!state.filename.includes('/.embroider/')) {
    return;
  }
}

But in a vite compat build ember-source lives at node_modules/.embroider/rewritten-packages/ember-source.*/node_modules/ember-source/..., so the path contains both /ember-source/ and /.embroider/ — the guard falls through and rewrites the file. min-supported didn't hit this on Ember 4.2 because that version's @ember/application doesn't import from @ember/owner in the first place.

Fix

Move the polyfill plugin out of the main plugins list into babel.overrides, with a test filter that skips anything whose filename contains /ember-source/:

     ...macros.babelMacros,
     ...(isCompatBuild
       ? [
           [
             'babel-plugin-debug-macros',
             {
               flags: [{ source: '@glimmer/env', flags: { DEBUG: true } }],
             },
           ],
-          'babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner',
         ]
       : []),
   ],

+  overrides: isCompatBuild
+    ? [
+        {
+          test: (filename) =>
+            filename !== undefined && !filename.includes('/ember-source/'),
+          plugins: [
+            'babel-plugin-ember-polyfill-get-and-set-owner-from-ember-owner',
+          ],
+        },
+      ]
+    : [],

This keeps the rewrite running where it's actually needed (@glimmer/[email protected]'s import { setOwner } from '@ember/owner', which is what #323 was targeting), and leaves ember-source alone.

A proper fix probably belongs upstream in the plugin (the existing filename guard likely intended to skip ember-source unconditionally), but this unblocks CI without needing a plugin release.

Test plan

• ember-lts-4.12 locally → 31 pass, 0 fail
• min-supported locally → 31 pass, 0 fail (polyfill still runs on @glimmer/component)
• Default non-compat → 31 pass, 0 fail (override block is empty)
• ember-lts-4.12 and min-supported jobs on CI go green
• Other try scenarios and the regular Tests/Floating jobs remain green

🤖 Generated with Claude Code